1. Technical Field of the Invention
The present invention relates to rake-type cleaning screens located in water conduits such as sewers, wastewater treatment streams, water treatment plants, power plants, and cooling water streams. More particularly, this invention relates to an improved bar screen for use with a rake type screen system.
2. Background of the Prior Art
Bar screens are used for screening solids and debris from flowing liquid streams. An example of such a bar screen system can be found in U.S. Pat. No. 5,730,862 issued to Mahr. In such systems, a series of rakes pass over parallel screen bars, which make up a bar screenfield and remove the debris collected from the flowing stream. Occasionally, large pieces of debris can damage the bar screenfield by either bending or breaking one or more bars within the bar screenfield. When this occurs, the screen system must be repaired by typically cutting out the affected bars and welding new bars in their place. These repair methods are time consuming, potentially hazardous, and expensive. The screen system is typically taken out of service for a relatively long period of time in order to make these repairs, which also adds significantly to the costs of the repairs.
A need exists for a screen system with bars that can be repaired quickly, safely, and cost effectively. Ideally, such a system should be capable of being adapted to the specific fluid applications and also be able to be used on existing screen system equipment with minimal modification.
The present invention advantageously provides a screen system for removing debris from a flow channel. The screen system includes a screen frame having a bar screenfield that is located below a debris plate. The bar screenfield includes a plurality of individually removable bars. Rakes with a plurality of fingers fit between the bars of the bar screenfield. The rakes are movable along the bar screenfield to clear the bar screenfield of debris.
The bars may be releasably secured in different ways to the frame of the screenfield. Preferably opposite ends of the bars fit within slots of a bar holder. After placement in the slots, a retainer with a plurality of teeth is secured to the holder. The gaps between the teeth are wedge-shaped for wedging the bars in place on the bar holder. The retainer is fastened to the bar holder with a releasable fastener.